Field of the Invention
Mechanical particle filters are used to extract particles for analysis from a fluid/particle mixture. However, now the particles are retained by the filter. The most common technique for removing particles from a filter for analysis is to introduce additional fluid, such as by using a backwashing process. However, ideally, the particles should be contained in the smallest amount of fluid possible while maintaining high retention ratio for ease of analysis. This is especially true when the particles are bacteria. Therefore, while backwashing a filter does remove the particles from the filter, the efficiency of the process is low and the quantity of fluid required may produce a secondary fluid/particle mixture with excessive fluid.
Furthermore, when using hydrophilic membrane with small pore size and when suction is provided on the downstream side of the filter to draw fluid and undersized particles, often times, the membrane will become a barrier to air after it was wetted.
A design and method are needed, whereby the particles of interest may be filtered and contained within a small volume of fluid and, furthermore, whereby the filter may be constructed such that, even after the fluid passes, the membranes of the filter will allow more suction using vacuum.